The role of money in elections is one of the most volatile fault lines in American politics. Liberals generally favor limits on how much gets raised for campaigns. Many conservatives want few if any restrictions.

Tuesday, the US Supreme Court is set to hear arguments about a Vermont law that goes a step further than limits on campaign contributions. It also restricts how much candidates can spend.

It's that limit on spending that makes the case, Randall v. Sorrell, so closely watched. The high court struck down such limits in a landmark case 30 years ago. But critics say that the explosive growth in campaign spending since that time has changed the political landscape.

"The time has come for the court to take a second look," says Brenda Wright of the National Voting Rights Institute in Boston. "What we had in Vermont that prompted this law was that there was a moment when the legislature and the citizenry felt that they were on the brink of slipping into the kind of special interest money- dominated politics that they saw at the national level and they did not want to see this happening to their state."

At issue in the Vermont case is the constitutionality of Act 64, a law passed by the state legislature in 1997 that seeks to break the connection between money and politics by establishing strict limitations on both campaign contributions and campaign expenditures.

Act 64 reflects a policy judgment by Vermont lawmakers that the best way to ensure a level playing field in elections is to slow the flow of money at both ends of the campaign pipeline.

Supporters of the law say such spending limits are justified by the government's interest in fostering citizen confidence in the democratic process by preventing corruption and the appearance of corruption.

"Under a system of unlimited campaign spending, incumbents amass war chests that deter challengers and leave many elections effectively uncontested," writes Ms. Wright in her brief to the court. This reduces officeholders' accountability and diminishes robust public debate on the issues, she adds.

Opponents of the law say that while some limitations on campaign contributions do not violate the First Amendment, restrictions on how much money a candidate can spend will muzzle candidates in violation of their free speech rights.

"The forced reduction in overall candidate campaign spending is illegitimate under the First Amendment," says James Bopp in his brief on behalf of the Vermont Republican State Committee challenging the Vermont law. "In the free society ordained by our Constitution it is not the government but the people ... who must retain control over the quantity and range of debate on public issues in a political campaign."

The Supreme Court has already limited the inflow of campaign funds. In 1976, it handed down a landmark decision recognizing that large cash contributions to candidates in the midst of political campaigns might give rise to corruption or the appearance of corruption. To counter it, the high court said in a case called Buckley v. Valeo that the government could place reasonable limits on the amount of money being contributed to a political campaign.

But the justices struck down limitations on the outflow of campaign funds - the amount of money candidates could spend while trying to get elected.

Legal analysts say it is unclear how the current court will approach the case. Some suggest Justice Anthony Kennedy may emerge as the swing vote with Chief Justice John Roberts and Justice Samuel Alito siding with conservatives Antonin Scalia and Clarence Thomas to strike down the Vermont law.

But others say the court may take a different approach, allowing lawmakers to make the policy choices of how best to conduct and finance elections.

There is little middle ground in the case. Opponents of the law say it amounts to an incumbent protection plan because challengers are barred from raising the amounts of money necessary to overcome the name recognition and other advantages of incumbency.

"Any expenditure ceiling - especially one that uses past average expenditures as the relevant guide - will necessarily restrict the spending of some candidates to ensure that other candidates are not outspent," says Mitchell Pearl, a Middlebury, Vt., lawyer in a brief urging the court to strike down the law. "Act 64 will prevent many candidates from amassing the resources necessary for effective advocacy."

In urging the high court to uphold Vermont's experiment in campaign finance reform, Vermont Assistant Attorney General Timothy Tomasi says spending limits help free candidates and officeholders from becoming beholden to campaign contributors.

"Expenditure limits militate against the undue access and influence now afforded donors and allow officials to decide issues based on the merits, not the wishes of their financiers," Mr. Tomasi writes in his brief. "They permit officials to attend to their public duties instead of seeking private dollars, and assure that candidates and officials have the opportunity to hear the views of all citizens, regardless of whether they are donors."